Proxy

package controller;
import java.util.Scanner;
//Returns a summary or the full book, based on the readers' age.

public class Demo {
    
    public static void main(String[] args) {
        LibraryProxy library = new LibraryProxy();
        System.out.println("What's your age");
        Scanner keyboard = new Scanner(System.in);
        int ageReader = keyboard.nextInt();
        library.returnBook(ageReader);

    }
}
class LibraryProxy implements Book{

    @Override
    public void returnBook(int age) {
        if (age<25){
            Book book = new emptyBook();
            book.returnBook(age);
        }else {
            Book book = new fullBook();
            book.returnBook(age);
        }

    }
}

class emptyBook implements Book{

    @Override
    public void returnBook(int age) {
        System.out.println("Returns the summary");
    }
}

class fullBook implements Book{

    @Override
    public void returnBook(int age) {
        System.out.println("Returns the full book");
    }
}

//////////interface////////////

public interface Book {
    void returnBook(int age);
}